In a blow to Gov. Chris Christieas authority, a state appeals court ruled today that the Republicanas administration broke the law when it said power plant operators no longer needed to comply with rules governing carbon dioxide emissions. Steam rises from the stack of the scrubber as the primary emission after the cleaning process ata coal-fired power plant outside Baltimore, Maryland, in this 2011 photo.

(Andre Chung/MCT)

TRENTON — In a blow to Gov. Chris Christie's authority, a state appeals court ruled today that his administration broke the law when it said power plant operators no longer needed to comply with rules meant to limit carbon dioxide emissions.

A three-judge appellate panel said the only way the administration can do this is by taking the step to repeal or change these rules — something that could be blocked by the state Legislature. It ordered the state Department of Environmental Protection to begin that process within 60 days.

The ruling was hailed by environmentalists and Democrats as a sharp rebuke of how Christie handled his 2011 decision to unilaterally pull New Jersey out of the Regional Greenhouse Gas Initiative, a multistate program meant to cut carbon dioxide pollution in the Northeast. The ruling does not force the state back into the program but does bring the issue to the fore once again, they said.

"I think this is a clear overreach by the Christie administration, and the court’s ruling quite simply says, ‘You cannot rule by fiat,’" said Doug O’Malley, the director of Environment New Jersey, one of the groups that filed the lawsuit.

The decision is also the latest of several stinging legal losses for Christie, whose administration has been rebuffed on public school funding, gay marriage and affordable housing. Recently, an appeals court threatened to jail one of his cabinet members if the state did not comply with its ruling, though the decision was later stayed.

This lawsuit was filed in 2012 in response to Christie’s withdrawal from the cap-and-trade program, known as RGGI. Within the program, each power plant is assigned an amount of carbon dioxide it can release, but the plants can buy or sell credits to increase or decrease emissions.

The groups that sued did not question Christie’s authority to withdraw from the program. But they said the state should have changed or repealed the rules that governed the state’s participation in it — rather tan simply posting a notice on its website. That would have allowed residents a chance to weigh in and the Legislature an opportunity to block the changes.

"The law must be followed," said Dale Bryk, director of energy and transportation for the National Resource Defense Council, which also brought the lawsuit. "There’s no excuse for not going through a public process to repeal a law."

She said the ruling could prompt Christie to reconsider the state’s participation in the program given that the federal Environmental Protection Agency is preparing tougher standards for power plants.

U.S. Sen. Robert Menendez (D-N.J.) said in a statement that he is optimistic the ruling would lead to improvements in the way New Jersey deals with climate change.

"These power plant limitations are an important piece of our regional answer to carbon pollution," Menendez said. "I hope that today’s decision will help keep the state at the forefront of the discussion on climate change and on the cutting edge of the clean energy sector."

The state did not say if it will appeal. A spokesman for the governor declined to comment and Lee Moore, a spokesman for the state Attorney General’s Office, said the decision was being reviewed.

The Republican governor, who says global warming is real and partly man-made, has called RGGI too weak to influence power plant operators and amounts to a tax on utility ratepayers. His administration has chosen instead to sue polluters in neighboring states, claiming they generate much of New Jersey’s air pollution.

The Democrat-controlled state Legislature could try to block the rule changes — a move that would, in theory, force the state to hold power plants accountable to the tougher emission standards under RGGI.

Assemblywoman Grace Spencer (D-Essex), who chairs the environment committee, said it’s something leaders in the lower house would consider. "Some of the rules that are in effect benefit the state as a whole, regardless of the participation in RGGI," Spencer said.

Lawmakers can stop the changes through two majority votes.

Jeff Tittel, the state director of the Sierra Club, predicted the ruling will be part of a protracted legal and political fight over whether New Jersey should be a part of the emissions program.

"This is sort of the beginning of a climate change chess game," Tittel said. "But it is a victory."